import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/**
 *	需要等待结果的线程
 */
public class CallableAndFuture {

	public static void main(String[] args) {
		//创建一个线程，用submit的方式提交任务，可以获得返回结果,结果不返回下面的无法执行
		ExecutorService threadPool = Executors.newSingleThreadExecutor();
		Future<String> future = 
			threadPool.submit(new Callable<String>(){
				public String call() throws Exception {
					Thread.sleep(5000);
					return "jobs have done!";
				}
			});
		
		System.out.println("等待结果...");
		try {
			System.out.println("结果是："+future.get());
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
		
		ExecutorService threadPool2 = Executors.newFixedThreadPool(10);
		CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(threadPool2);
		for(int i=0;i<10;i++){
			final int seq = i;
			completionService.submit(new Callable<Integer>(){
				public Integer call() throws Exception {
					Thread.sleep(new Random().nextInt(5000));
					return seq;
				}
			});
		}
		
		System.out.println("waiting for result ... ");
		
		for(int i=0;i<10;i++){
			try {
				System.out.println("get result : "+completionService.take().get());
			} catch (InterruptedException e) {
				e.printStackTrace();
			} catch (ExecutionException e) {
				e.printStackTrace();
			}
		}
		
	}

}
